This invention relates to medical tube assemblies.
The invention is more particularly concerned with tube assemblies of the kind comprising an outer tube and an inner tube insertable into and removable from the machine end of the outer tube.
Tracheostomy tubes are often provided with a removable inner cannula. When secretions accumulate inside the assembly, the inner cannula can be removed and replaced. This avoids the need to replace the outer tube, which would be more traumatic and would have to be carried out by a doctor. Tracheostomy tubes are provided in a range of different characteristics for use in different situations. For example, the tubes can be made of different materials, different shapes, can be reinforced or unreinforced or can be of different sizes. Also, in a hospital, tubes may be available from different manufacturers. The outer tubes of different characteristics require different size inner cannulae. There is a risk, with conventional assemblies, that a nurse or other practitioner could replace an inner cannula with a cannula of the wrong characteristic or type. For example, an inner cannula intended for use in a reinforced outer tube might be wrongly inserted in an unreinforced tube. This could cause a poor fit or damage to the inner cannula or outer tube.